Apparatus, method, and manufacture for connectable gain-sharing automixers

ABSTRACT

A device for audio mixing includes a cascade input port and a first cascade input component that includes a first cascade input level detector component that detects an audio level of an upstream sum audio signal. The first cascade input port also includes an attenuator component that attenuates the first upstream mix audio signal by a gain corresponding to difference between the upstream sum audio signal value and a detected audio level of an input sum audio signal. The device also includes a summer component where the signals summed include at least the first upstream sum audio signal. The device also includes an input sum level detector component that detects the audio level of the input sum audio signal. The device also includes a mixer component that is configured to provide a mix output signal by summing, where the signals summed include at least the first attenuated upstream mix signal.

FIELD OF THE INVENTION

The invention is related to sound control systems, and in particular, toan apparatus, method, and manufacture for gain-sharing automixing ofaudio signals that allow the addition of more automixer inputs to theautomixer by simply connecting one or more distributed gain-sharingautomixers.

BACKGROUND OF THE INVENTION

An automixer is typically designed to balance multiple sound sources,usually microphones, based on the level of each source, attenuatinginactive inputs. Automixers are typically used to mix panel discussionson television shows and at conferences and seminars. They can also beused to mix actors' wireless microphones in theater productions andmusicals. They may be used in audio systems in churches, schools,hotels, convention centers, and the like. They are frequently employedin commercial sound systems such as in courtrooms and city councilchambers where it is not expected that a live sound operator will bepresent to mix the microphones. When automixers are used in live soundreinforcement, they work to maintain a steady limit on the overallsignal level of the microphones. If a public address system is set up sothat one microphone will not feed back, then, in general, multiplemicrophones will not feed back if they are automixed.

Further, various gain-sharing strategies have been developed in whichthe signal level in a particular channel is compared with the sum of allthe channels to compute a gain-sharing factor. The channel with thehighest level input receives highest gain which is a proportionalfraction of the total gain available. Additionally, gain-sharingstrategies have been developed in which a proportional, multichannelgain-sharing audio circuit has a gain control in the computing leg sothat additional weight may be accorded the channel so that the channelis allocated greater gain in proportion to the total amount of signalavailable to all of the channels combined.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings, in which:

FIG. 1 illustrates a block diagram of an embodiment of an automixer;

FIG. 2 shows a block diagram of an embodiment of the automixer of FIG.1;

FIG. 3 illustrates a block diagram of an embodiment of a system thatincludes automixers that are embodiments of the automixer of FIG. 1 orFIG. 2; and

FIG. 4 shows a block diagram of an embodiment of a system that includesan embodiment of the automixer of FIG. 1 or FIG. 2, arranged inaccordance with aspects of the invention.

DETAILED DESCRIPTION

Various embodiments of the present invention will be described in detailwith reference to the drawings, where like reference numerals representlike parts and assemblies throughout the several views. Reference tovarious embodiments does not limit the scope of the invention, which islimited only by the scope of the claims attached hereto. Additionally,any examples set forth in this specification are not intended to belimiting and merely set forth some of the many possible embodiments forthe claimed invention.

Throughout the specification and claims, the following terms take atleast the meanings explicitly associated herein, unless the contextdictates otherwise. The meanings identified below do not necessarilylimit the terms, but merely provide illustrative examples for the terms.The meaning of “a,” “an,” and “the” includes plural reference, and themeaning of “in” includes “in” and “on.” The phrase “in one embodiment,”as used herein does not necessarily refer to the same embodiment,although it may. Similarly, the phrase “in some embodiments,” as usedherein, when used multiple times, does not necessarily refer to the sameembodiments, although it may. As used herein, the term “or” is aninclusive “or” operator, and is equivalent to the term “and/or,” unlessthe context clearly dictates otherwise. The term “based, in part, on”,“based, at least in part, on”, or “based on” is not exclusive and allowsfor being based on additional factors not described, unless the contextclearly dictates otherwise. The term “coupled” means at least either adirect electrical connection between the items connected, or an indirectconnection through one or more passive or active intermediary devices.The term “signal” means at least one current, voltage, charge,temperature, data, audio, or other signal.

Briefly stated, the invention is related to a device for audio mixingthat includes a cascade input port and a first cascade input componentthat includes a first cascade input level detector component thatdetects an audio level of an upstream sum audio signal. The firstcascade input port also includes an attenuator component that attenuatesthe first upstream mix audio signal by a gain corresponding todifference between the upstream sum audio signal value and a detectedaudio level of an input sum audio signal. The device also includes asummer component where the signals summed include at least the firstupstream sum audio signal. The device also includes an input sum leveldetector component that detects the audio level of the input sum audiosignal. The device also includes a mixer component that is configured toprovide a mix output signal by summing, where the signals summed includeat least the first attenuated upstream mix signal.

The automixer may accordingly act as a distributed gain-sharingautomixer that enables the addition of more automixer inputs to anautomixer by simply connecting one or more distributed gain-sharingautomixers. This allows for distributing the inputs, outputs, andprocessing of a single, gain-sharing, automatic microphone mix across anumber of different physical automixers. A variety of devices inaccordance with embodiments of the invention may have various input,output, and processing capabilities that may be connected together toproduce an automatic mix of the microphone inputs on all interconnectedproducts, and the devices may be used to build audio systems of varioussizes (inputs, outputs, processing) that include gain-sharing automaticmicrophone mixing.

FIG. 1 illustrates a block diagram of an embodiment of automixer 100,which may include cascade input port 101, cascade input component 111,input summer component 120, and mixer component 130. Cascade inputcomponent 111 includes cascade input level detector component 151,attenuator component 161, and cascade gain computation component 171.Input summer component 120 includes summer component 121 and input sumlevel detector component 150. Mixer component 130 includes summercomponent 122.

Cascade input port 101 is configured to receive a first upstream sumaudio signal Upstream-sum and a first upstream mix audio signalUpstream-mix. These signals, when present, are generated from anotherautomixer, which may be substantially similar to automixer 100 of FIG. 1or automixer 200 of FIG. 2.

FIG. 1 illustrates one cascade input for automixer 100. Automixer 100has at least two inputs, which may include two or more cascade inputs,two or more microphone inputs, or at least one cascade input and atleast one microphone input. FIG. 1 shows only a single cascade input,because the additional input(s) may be either at least one additionalcascade input, at least one microphone input, or both. FIG. 2 shows anautomixer with any number of microphone inputs and any number of cascadeinputs. FIG. 1 shows a simple embodiment with only one cascade inputactually shown in the figure, with further inputs unspecified.Accordingly, automixer 100 may have one cascade input, and one or moreadditional inputs (cascade, microphone, or both). Alternatively, otherembodiments of automixer 100 may have two or more microphone inputs, andno cascade inputs (but having a cascade output). For examples, AutomixerA, B, and C of FIG. 3 are embodiments of automixer 100 that each havemultiple microphone inputs, no cascade inputs, and each have a cascadeoutput.

Input level detector component 151 is configured to provide a detectedvalue (shown as “Level of Upstream-sum” in FIG. 1) corresponding to anaudio level of Upstream-sum. Cascade gain computation component 171 isconfigured to provide a first cascade gain value, GainCI1, correspondingto a difference between the value of the detected audio level of signalUpstream-sum (“Level of Upstream-sum”) and an input sum level value(shown in FIG. 1 as “Level of Sum of All Inputs”). Attenuator component161 is configured to provide a first attenuated upstream mix signal AUM1by attenuating first upstream mix audio signal Upstream-mix based onfirst cascade gain value GainCI1.

Summer component 121 is configured to provide an input sum audio signal(shown as “Sum of All Inputs” in FIG. 1) by summing together each signalprovided as an input to the summer component, where at least firstupstream sum audio signal Upstream-sum is provided as an input to thesummer component. Input sum level detector component 150 is configuredto provide the input sum level value (“Level of Sum of All Inputs”)corresponding to an audio level of the input sum audio signal. Mixercomponent 130 is configured to provide mix output signal Mix Output bysumming together each signal provided as an input to the mixercomponent, where at least first attenuated upstream mix signal AUM1 isprovided as an input to the mixer component.

FIG. 2 shows a block diagram of an embodiment of automixer 200, whichmay be employed as an embodiment of automixer 100 of FIG. 1. Automixer200 is similar to automixer 100 of FIG. 1, but it includes n microphoneinputs and m cascade inputs, where n and m are both integers, n isgreater than or equal to zero, m is greater than or equal to zero, andthe sum of n+m is greater than or equal to 2.

Each cascade input component (e.g., 211) operates in a substantiallysimilar manner as discussed above with regard to cascade input component111 of FIG. 1, with each separate cascade input component receiving aseparate Upstream-sum signal, receiving a separate Upstream-mix signal,and providing a different attenuated Upstream-mix signal (AUM1-AUMm).

Microphone input 281 is configured to receive microphone input audiosignal Microphone Input. A microphone audio input is any audio signalinput to automixer 200 that is not the output of an upstream automixerand for which gain-sharing is to be performed. Typically the input isfrom a microphone, but the invention is not so limited, and as statedthe “microphone” input may be an audio input that is not the output ofan upstream automixer for which gain-sharing is to be performed. Firstmicrophone input level detector component 252 is configured to provide adetected value (shown as “Level of Microphone Input” in FIG. 2)corresponding to an audio level of Microphone Input. First microphonegain computation component 272 is configured to provide a firstmicrophone gain value (GainM1) corresponding to a difference betweenLevel of Microphone Input and Level of Sum of All Inputs. Firstmicrophone attenuation component 262 is configured to provide firstattenuated microphone input signal AMI1 by attenuating Microphone Inputbased on GainM1.

Each of the n microphone inputs is configured to operate in asubstantially similar manner as discussed above with regard tomicrophone input 281, with each separate microphone input receiving aseparate microphone input audio signal, and providing a separateattenuated microphone input signal (AMI1-AMIn).

Input summer component 221 is configured to provide the input sum audiosignal (“Sum of All Inputs”) by summing together each of the nMicrophone Input signals and each of the m Upstream-sum signals. Mixercomponent 230 is configured to provide signal Mix Output by summingtogether each of the m attenuated upstream signals AUM1-AUMm and each ofthe n attenuated microphone input signals MI1-MIn. The cascade outputsignal Cascade Output includes two audio signals: Mix Output and theinput sum audio signal. The cascade output signal may be routed to thecascade input of another automixer 200.

In some embodiments, each of the level detector components (e.g., 250,251, and 252) is configured to monitor an audio signal and continuallyprovide a value representing the level of the monitored audio signal indB. In some embodiments, the root mean square (gins) value of the audiolevel is detected over a continuous rolling time window on the order ofabout 20 ms and a corresponding value is provided as the level of themonitored audio signal in dB. In other embodiments, other mathematicalrelationships and/or other time periods may be employed. The units ofthe audio level are not relevant—if signal Upstream-sum is an analogsignal having a voltage that is proportional to the correspondingacoustical pressure of the sound produced if the audio signal were usedto drive a speaker, then input level detector component 151 detectsvoltage (e.g., rms voltage); if signal Upstream-sum is a digital signal,input level detector component 151 detects the digital value (e.g., therms of the digital value) representing the audio level. In someembodiments, each gain computation component (e.g. 271 and 272) providesa value representing the difference in dB between the outputs of twolevel detector components.

In some embodiments of automixer 200, microphone input audio signals areacquired via microphone preamplifiers and analog to digital converters,before entering a 32-bit, floating-point, digital signal processor(DSP). In some embodiments, the cascade input audio signals enter via astereo digital audio input port encoded as a stream of uncompressed,32-bit, audio samples represented as floating-point values. In someembodiments, each of the level detector components, gain computationcomponents, attenuation components, and summer components areimplemented in the floating-point DSP. In some embodiments, the audiosignals of the cascade output are output from automixer 200 via a stereodigital audio output port, encoded as a stream of uncompressed, 32-bit,audio samples represented as floating-point values.

In some embodiments of automixer 200, the uncompressed digital audio ofthe cascade output and cascade input are encoded as streams ofuncompressed, two's complement, 24-bit, fixed-point values, encodedusing the Audio Engineering Society 3 (AES3) standard for digital audioinput-output interfacing. This implementation allows the designer toleverage the built-in features of the floating-point DSP that expectsdata entering over synchronous serial audio ports to be represented astwo's complement, 24-bit, fixed point values.

In some embodiments, some or all the components of automixer 200 (e.g.,level detector components, gain computation components, attenuationcomponents, and summer components) may be implemented using analogelectronics instead of a DSP. For example, summing components as well asthe gain computation components can be implemented by a summingamplifier such as an op amp summing circuit, or the like; and/or theattenuator components may be implemented with a voltage controlledamplifier, and/or the like. For example, in one embodiment, attenuationcomponent 261 of FIG. 2 may be implemented by a voltage controlledamplifier that is arranged to receive signal Upstream-sum at an input ofthe voltage controlled amplifier, to receive GainCI1 at a gain input ofthe voltage-controlled amplifier, and to provide the signal AUM1 at theoutput of the voltage controlled amplifier

Various embodiments of automixer 200 may be entirely encoded in adigital signal processor, and/or encoded as processor executable codestored in processor-executable memory together with one or moreprocessors arranged to execute the software, may be all analogcomponents, or may be some combination of hardware components andsoftware components stored in memory to be executed by one or moreprocessors in automixer 200. Processor-readable code may be encoded on aprocessor readable medium for performing the actions of automixer 200when executed by one or more processors.

Automixer 200 enables the addition of more automixer inputs by simplyconnecting one or more automixers 200. Each distributed automixer 200accepts audio inputs, such as microphone inputs, cascade inputs from thecascade outputs of other distributed automixers 200, and/or the like.The group of distributed automixers accepts audio inputs, such asmicrophone inputs, and mixes together the audio from those inputs via again-sharing algorithm. Using a gain-sharing automatic mixing algorithmprovides several benefits. First, the algorithm produces a mix that hasa constant gain from all inputs to the output. When the gain of thesystem is constant, an operator can create a public address system inwhich the acoustic gain is constant, and equal to the Needed AcousticGain (NAG). In such a system, the Feedback Stability Margin (FSM) may bemaximized, and remains constant regardless of the number of microphones.Also, in a system where background noise is detected evenly by allmicrophones, a gain-sharing algorithm produces a constant level ofbackground noise at the mix output regardless of the number ofmicrophones or their input signal levels. In other words, thegain-sharing algorithm produces no gating, pumping, or breathing effectsin the reinforced background noise of the public address system. Again-sharing algorithm also reduces the comb filtering effect producedby two or more microphones detecting the same acoustic signal. Usingautomixer 200 for distributing a gain-sharing automix across multipledevices, the gain-sharing algorithm and all of its benefits arepreserved even though the mixing and inputs are shared among variousphysical devices.

Automixer 200 enables a method for distributing a gain-sharing automaticmix across a variety of series connected devices by sending theresulting automatic mix (mix(n−1)) and the sum of all inputs (sum(n−1))from one mixer (mixer(n−1)) to the next mixer in the series (mixer(n))where sum(n−1) is summed with all other inputs of mixer(n) to create anew sum(n). Mixer(n) then attenuates the signal mix(n−1) by the relativedifference in dB between sum(n) and sum(n−1), before mixing it with theother mixer(n) inputs which have been attenuated by the difference in dBbetween their levels and the level of sum(n), producing the new outputmix(n). Mix(n) and sum(n) may be sent to mixer(n+1) and so on. Theresult is a gain-sharing automatic mix(n) at the output of any mixer(n)that includes all inputs from mixer(0) to mixer(n).

Distributing the inputs and processing of automixer 200 allows theseries combination of an arbitrary number of gain-sharing automixersthat each produce a gain-sharing automix at each automixer's output ofall inputs up to and including that automixer's. For example, in asystem with three automixers 200 connected in series, audio flows fromMixer1 to Mixer2 to Mixer3. Connecting three automixers 200 in seriesmay be accomplished by connecting the cascade output of Mixer1 to thecascade input of Mixer2, and connecting the cascade output of Mixer2 tothe cascade input of Mixer3. Mixer1's output is a gain-sharing mix ofits inputs. Mixer2's output is a gain-sharing mix of the inputs onMixer1 and Mixer2. Mixer3's output is a gain-sharing mix of the inputson Mixer1, Mixer2, and Mixer3. The processing required in any oneautomixer 200 does not change with the addition of more automixers 200in the series chain. Also, in some embodiments, the series interconnectbetween each automixer consists of two audio channels regardless of thenumber of automixers in the chain. Further, there is no master/slaverelationship between automixers 200. Further, the gain computation foreach microphone input does not require each microphone input to know thelevel in dB of the sum of all inputs on all automixers, and accordinglythere is no need for a signal that flows back up the series chain fromthe last device representing the level of the sum of all inputs, andstandard methods of stereo interconnect may be used for interconnectingthe automixers 200 in the system.

Some embodiments of automixer 200 contain more than one cascade input.As automixers 200 are interconnected in topologies other than a simpledaisy-chain, it remains true that the output of any automixer 200 is again-sharing automix of all mixer microphone inputs and upstreammicrophone inputs. The cascade input and cascade outputs are used todistribute the gain-sharing automixes across multiple devices in eachtopology. The Mix Output of any automixer in the system is again-sharing automix of all the mixer input and upstream inputs that isindependent of downstream inputs. Virtually any topology of devices maybe used—however a ring topology should not be employed—the cascadeoutput of one automixer 200 may be used as the cascade input of anyother automixer 200 unless that automixer 200 is already upstream, i.e.,audio signals from that automixer 200 are already included as part ofthe gain-sharing mix of the automixer 200.

Various embodiments of automixer 200 may be employed as a variety ofdevices with gain-sharing automatic mixing capability that may becombined to create larger systems. Further, the processing capability ofeach product may be designed without concern for the number or type ofdistributed automixers 200. The various automixers 200 can use simple,low-cost, off-the-shelf solutions for stereo digital audio distributionto implement the series automixer interconnect between products.Further, use of automixers 200 simplifies the installation ofinterconnected products because the installer does not need to specify amaster device.

The output of a system of distributed automixers 200 is the same resultas if all of the inputs were provided to a single automixer 200, asillustrated by the following examples.

If a four input automixer has all four inputs driven with non-coherent10 dBu signals, the sum of all these inputs has an rms level of 16 dBu.According to the gain-sharing equation, each input must be attenuated bythe difference in dB between its level and the level of the sum (6 dB).Accordingly, each input is attenuated by 6 dB, and then they are mixedtogether to produce the output of the automixer.

If the same inputs were provided to two distributed automixers 200connected together, with two 10 dBu inputs to each automixer 200, theupstream mixer sums the two microphone inputs and its unused cascadeinput, resulting in an Upstream-sum signal with an rms level of 13 dBu.Each microphone input is attenuated by 3 dB and the resulting mix ispresent at the automixer's output. Signals Upstream-sum and Upstream-mixare sent to the downstream automixer via standard stereo audiointerconnect. The downstream automixer sums its two microphone inputsand its cascade input's Upstream-sum signal to produce a sum of allinputs with an rms level equal to 16 dBu. Each microphone input isattenuated by 6 dB, and signal Upstream-mix is attenuated by 3 dB. Thethree attenuated signals are mixed together to create the downstreamautomixer's output. The output mix of the downstream automixer includesall four inputs, each attenuated by 6 dB as required by the gain-sharingalgorithm. The upstream microphone inputs were attenuated by 3 dB in theupstream automixer and 3 dB at the cascade input to the downstreamautomixer, while the downstream microphone inputs were attenuated by 6dB in the downstream automixer. Further, the output of the upstreamautomixer is an accurate gain-sharing mix of its two inputs that isunaffected by downstream inputs. Also, as previously discussed, there isno need for an interconnect or user controls required to send the levelof the sum of all inputs back up stream, which enables the use ofstandard stereo audio interconnect to connect the cascade output of theupstream automixer to the cascade input of the downstream automixer.

In some embodiments, microphone inputs within a single system may bepartitioned into groups that may be combined or separated into differentgain-sharing mixes. In such a system, several automixers 200 withmicrophone and/or cascade inputs may be used to collect inputs from thesystem. The cascade outputs of these automixers may be routed to theinputs of one or more downstream automixers 200 that have only cascadeinputs. The inputs of upstream automixers 200 may be combined intogain-sharing mixes at the output of the downstream automixers 200 indifferent configurations by muting signals Upstream-sum and Upstream-mixsignals at the cascade input to the downstream automixer. One example ofsuch a system is illustrated in FIG. 3 below.

FIG. 3 illustrates a block diagram of an embodiment of system 305, whichincludes automixers A-F and mute switches 399, where each of theautomixers A-F may be an embodiment of automixer 100 of FIG. 1 orautomixer 200 of FIG. 2.

As shown, Automixer A is used for receiving microphone inputs 1-4,Automixer B is used for receiving microphone inputs 5-7, and automixer Cis used for receiving microphone inputs 8 and 9. The cascade outputs ofAutomixers A-C are coupled via mute switches to the cascade inputs ofAutomixers D-F to selectively provide different automatic mixes of themicrophone, including the possibility of achieving an automatic mix ofall of the microphone inputs.

FIG. 4 shows a block diagram of an embodiment of system 406. System 406includes two or more automixers 400, which may each be an embodiment ofautomixer 100 of FIG. 1 or automixer 200 of FIG. 2, as well as variousperipheral components. The peripheral components may include wiredmicrophones 490, MP3 player 492, DVD player 493, wireless receive 494,wireless microphone 495, and/or the like. As shown, in some embodiments,a variety of audio sources may be used, with gain-sharing performed formicrophone inputs, including wired microphones 490 and wirelessmicrophones 495, which may be connected by wireless receivers in someembodiments. The mix output of any of the automixers 400 may be providedto a speaker, such as powered speaker 491, for outputting the mixedaudio signal from the speaker.

The above specification, examples and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

1. A device for audio mixing, comprising: an input port that is arrangedto receive at least a first audio signal; a first input component,including: a first input level detector component that is configured toprovide a detected value; a first gain computation component that isconfigured to provide a first gain value corresponding to a differencebetween the detected value and an input sum level value; and anattenuator component that is configured to provide a first attenuatedinput audio signal by attenuating the input audio signal based on thefirst gain value; a summer component that is configured to provide aninput sum audio signal by summing together each signal provided as aninput to the summer component, wherein at least the first audio signalis provided as an input to the summer component; an input sum leveldetector component that is configured to provide the input sum levelvalue corresponding to an audio level of the input sum audio signal; anda mixer component that is configured to provide a mix output signal bysumming together each signal provided as an input to the mixercomponent, wherein at least the first attenuated input audio signal isprovided as an input to the mixer component.
 2. A device for audiomixing, comprising: a cascade input port that is configured to receive afirst upstream sum audio signal and a first upstream mix audio signal; afirst cascade input component, including: a first cascade input leveldetector component that is configured to provide an upstream sum levelvalue corresponding to an audio level of the upstream sum audio signal;a first cascade gain computation component that is configured to providea first cascade gain value corresponding to a difference between theupstream sum level value and an input sum level value; and a firstcascade attenuator component that is configured to provide a firstattenuated upstream mix signal by attenuating the first upstream mixaudio signal based on the first cascade gain value; a summer componentthat is configured to provide an input sum audio signal by summingtogether each signal provided as an input to the summer component,wherein at least the first upstream sum audio signal is provided as aninput to the summer component; an input sum level detector componentthat is configured to provide the input sum level value corresponding toan audio level of the input sum audio signal; and a mixer component thatis configured to provide a mix output signal by summing together eachsignal provided as an input to the mixer component, wherein at least thefirst attenuated upstream mix signal is provided as an input to themixer component.
 3. The device of claim 2, wherein the first cascadeinput level detector component is configured to provide the upstream sumlevel value such that the audio level of the upstream sum audio signalis a root mean square audio level of the upstream sum audio signal, andwherein the input sum level detector component is configured to providethe input sum level such that the audio level of the input sum audiosignal is the root mean square audio level of the input sum audiosignal.
 4. The device of claim 2, wherein the device further includes adigital signal processor, and wherein the digital signal processorincludes the first cascade input component, the summer component, theinput sum level detector component, and the mixer component.
 5. Thedevice of claim 2, wherein the first cascade attenuator component is avoltage controlled amplifier having a first input, a gain input, and anoutput, wherein the voltage controlled amplifier is arranged to receivethe first upstream mix audio signal at the input of the voltagecontrolled amplifier, to receive the first cascade gain value at thegain input of the voltage-controlled amplifier, and to provide the firstattenuated upstream mix signal at the output of the voltage controlledamplifier.
 6. The device of claim 2, further comprising: a secondcascade input component, including: a second cascade input leveldetector component that is configured to provide a second upstream sumlevel value corresponding to an audio level of a second upstream sumaudio signal, wherein the second upstream sum audio signal is alsoprovided as an input to the summer component; a second cascade gaincomputation component that is configured to provide a second cascadegain value corresponding to a difference between the second upstream sumlevel value and the input sum level value; and a second cascadeattenuator component that is configured to provide a second attenuatedupstream mix signal by attenuating the second upstream mix audio signalbased on the second cascade gain value, wherein the second attenuatedupstream mix signal is also provided as an input to the mixer component.7. The device of claim 2, further comprising: a first microphone inputcomponent, including: a first microphone input level detector componentthat is configured to provide a first microphone input level valuecorresponding to an audio level of a first microphone input audiosignal, wherein the first microphone input audio signal is also providedas an input to the summer component; a first microphone gain computationcomponent that is configured to provide a first microphone gain valuecorresponding to a difference between the first microphone input levelvalue and the input sum level value; and a first microphone attenuatorcomponent that is configured to provide a first attenuated microphoneinput signal by attenuating the first microphone input audio signalbased on the first microphone gain value, wherein the first attenuatedmicrophone input signal is also provided as an input to the mixercomponent.
 8. The device of claim 7, further comprising: a secondmicrophone input component, including: a second microphone input leveldetector component that is configured to provide a second microphoneinput level value corresponding to an audio level of a second microphoneinput audio signal, wherein the second microphone input audio signal isalso provided as an input to the summer component; a second microphonegain computation component that is configured to provide a secondmicrophone gain value corresponding to a difference between the secondmicrophone input level value and the input sum level value; and a secondmicrophone attenuator component that is configured to provide a secondattenuated microphone input signal by attenuating the second microphoneinput audio signal based on the second microphone gain value, whereinthe second attenuated microphone input signal is also provided as aninput to the mixer component.
 9. A method for audio mixing, comprising:providing an upstream sum level value corresponding to an audio level ofan upstream sum audio signal; providing a first cascade gain valuecorresponding to a difference between the upstream sum level value andan input sum level value; providing a first attenuated upstream mixsignal by attenuating the first upstream mix audio signal based on thefirst cascade gain value; providing an input sum audio signal by summingtogether a plurality of summing input signals, wherein the plurality ofsumming input signals include at least the first upstream sum audiosignal; providing the input sum level value corresponding to an audiolevel of the input sum audio signal; and providing a mix output signalby summing together a plurality of mixer input signals, wherein theplurality of mixer input signals include at least the first attenuatedupstream mix signal.
 10. The method of claim 9, wherein providing theupstream sum level value is accomplished such that the audio level ofthe upstream sum audio signal is a root mean square audio level of theupstream sum audio signal, and wherein providing the input sum level isaccomplished such that the audio level of the input sum audio signal isthe root mean square audio level of the input sum audio signal.
 11. Themethod of claim 9, further comprising: providing a second upstream sumlevel value corresponding to an audio level of a second upstream sumaudio signal, wherein the plurality of summing input signals furtherinclude at least the second upstream sum audio signal; providing asecond cascade gain value corresponding to a difference between thesecond upstream sum level value and the input sum level value; andproviding a second attenuated upstream mix signal by attenuating thesecond upstream mix audio signal based on the second cascade gain value,wherein the plurality of mixer input signals further include at leastthe second attenuated upstream mix signal.
 12. The method of claim 9,further comprising: providing a first microphone input level valuecorresponding to an audio level of a first microphone input audiosignal, wherein the plurality of summing input signals further includeat least the first microphone input audio signal; providing a firstmicrophone gain value corresponding to a difference between the firstmicrophone input level value and the input sum level value; andproviding a first attenuated microphone input signal by attenuating thefirst microphone input audio signal based on the first microphone gainvalue, wherein the plurality of mixer input signals further include atleast the first attenuated microphone input signal.
 13. The method ofclaim 12, further comprising: providing a second microphone input levelvalue corresponding to an audio level of a second microphone input audiosignal, wherein the plurality of summing input signals further includeat least the second microphone input audio signal; and providing asecond microphone gain value corresponding to a difference between thesecond microphone input level value and the input sum level value; andproviding a second attenuated microphone input signal by attenuating thesecond microphone input audio signal based on the second microphone gainvalue, wherein the plurality of mixer input signals further include thesecond attenuated microphone input signal.
 14. A manufacture including aprocessor-readable medium having processor-executable code encodedtherein, which when executed by one or more processors, enables actionsfor audio mixing, comprising: providing an upstream sum level valuecorresponding to an audio level of an upstream sum audio signal;providing a first cascade gain value corresponding to a differencebetween the upstream sum level value and an input sum level value;providing a first attenuated upstream mix signal by attenuating thefirst upstream mix audio signal based on the first cascade gain value;providing an input sum audio signal by summing together a plurality ofsumming input signals, wherein the plurality of summing input signalsinclude at least the first upstream sum audio signal; providing theinput sum level value corresponding to an audio level of the input sumaudio signal; and providing a mix output signal by summing together aplurality of mixer input signals, wherein the plurality of mixer inputsignals include at least the first attenuated upstream mix signal. 15.The manufacture of claim 14, wherein the enabled actions furtherinclude: providing a second upstream sum level value corresponding to anaudio level of a second upstream sum audio signal, wherein the pluralityof summing input signals further include at least the second upstreamsum audio signal; providing a second cascade gain value corresponding toa difference between the second upstream sum level value and the inputsum level value; and providing a second attenuated upstream mix signalby attenuating the second upstream mix audio signal based on the secondcascade gain value, wherein the plurality of mixer input signals furtherinclude at least the second attenuated upstream mix signal
 16. Themanufacture of claim 14, wherein the enabled actions further include:providing a first microphone input level value corresponding to an audiolevel of a first microphone input audio signal, wherein the plurality ofsumming input signals further include at least the first microphoneinput audio signal; providing a first microphone gain valuecorresponding to a difference between the first microphone input levelvalue and the input sum level value; and providing a first attenuatedmicrophone input signal by attenuating the first microphone input audiosignal based on the first microphone gain value, wherein the pluralityof mixer input signals further include at least the first attenuatedmicrophone input signal.
 17. The manufacture of claim 16, wherein theenabled actions further include: providing a second microphone inputlevel value corresponding to an audio level of a second microphone inputaudio signal, wherein the plurality of summing input signals furtherinclude at least the second microphone input audio signal; and providinga second microphone gain value corresponding to a difference between thesecond microphone input level value and the input sum level value; andproviding a second attenuated microphone input signal by attenuating thesecond microphone input audio signal based on the second microphone gainvalue, wherein the plurality of mixer input signals further include thesecond attenuated microphone input signal.
 18. A system for audiomixing, comprising: a first automixer having at least a cascade outputport; and a second automixer, including: a cascade input port that isarranged to receive a first upstream sum audio signal and a firstupstream mix audio signal from the cascade output port of the firstautomixer; a first cascade input component, including: a first cascadeinput level detector component that is configured to provide an upstreamsum level value corresponding to an audio level of the upstream sumaudio signal; a first cascade gain computation component that isconfigured to provide a first cascade gain value corresponding to adifference between the upstream sum level value and an input sum levelvalue; and a first cascade attenuator component that is configured toprovide a first attenuated upstream mix signal by attenuating the firstupstream mix audio signal based on the first cascade gain value; asummer component that is configured to provide an input sum audio signalby summing together each signal provided as an input to the summercomponent, wherein at least the first upstream sum audio signal isprovided as an input to the summer component; an input sum leveldetector component that is configured to provide the input sum levelvalue corresponding to an audio level of the input sum audio signal; anda mixer component that is configured to provide a mix output signal bysumming together each signal provided as an input to the mixercomponent, wherein at least the first attenuated upstream mix signal isprovided as an input to the mixer component.